The present invention relates to a method of making a spinner disc for a rotary fiberization process, such as but not limited to a glass fiberization process, and, in particular, to a method which includes: forming a spinner disc from an alloy that forms a protective oxide film or films on surfaces of the alloy exposed to the atmosphere; and plasma treating a surface of the spinner disc with charged particles to remove hydrocarbons and sulfurous compounds from the surface of the spinner disc which would otherwise reduce and/or react with and degrade the protective oxide film(s) forming on the surface of the spinner disc when the spinner disc is exposed to the atmosphere.
Elevated temperature resistant alloys such as but not limited to stainless iron, nickel and cobalt alloys are typically used as the alloys for spinner discs in elevated temperature rotary fiberization processes such as glass fiberization processes. In rotary glass fiberization processes, spinner discs made from these elevated temperature resistant alloys typically operate at temperatures of about 1800xc2x0 F. and greater. The cobalt alloys are normally preferred for this application because of the superior performance of such cobalt alloys in this application when compared to iron or nickel based alloys. The superior performance of the cobalt alloys is due to their higher strength and creep resistance at the elevated temperatures used in rotary glass fiberization processes and their greater corrosion resistance at the elevated temperatures used in rotary glass fiberization processes.
These elevated temperature resistant alloys, e.g. stainless iron, nickel and cobalt alloys, when exposed to the air or atmosphere, form thin continuous, protective oxide films, such as but not limited to a strong, thin and continuous Cr2O3 barrier film, that protect the alloys from corrosion. The formation of high quality continuous oxide films with overall good integrity on the surfaces of the spinner discs is essential for superior corrosion resistance.
In the fabrication of the spinner discs used in rotary glass fiberization processes, typically, the spinner discs are cast. The surfaces of spinner disc castings are then machined and fiberizing holes are drilled, e.g. twist, electron beam, laser, EDM, etc., through the annular peripheral sidewalls of the spinner discs. After the spinner disc castings have been machined and the fiberizing holes have been drilled, the spinner discs are solvent cleaned and dried to remove the bulk of the hydrocarbon and sulfurous contaminants typically present on the surfaces of the spinner discs at this point of the manufacturing process. The spinner discs are then heat treated to build up a protective oxide film or films on the surfaces of the spinner discs and to strengthen the alloy, prior to being put into operation.
While the above described process removes the bulk of the hydrocarbon and sulfurous contaminants from the surfaces of the spinner discs, trace quantities of hydrocarbon and sulfurous contaminants remain on the surfaces of the spinner discs after solvent cleaning. The protective oxide films which form on these elevated temperature resistant alloys are adversely affected by these trace quantities of hydrocarbon and sulfurous contaminants on the alloy surface which volatilize, decompose and interact with the oxide films upon heating. For example, partially combusted hydrocarbons will locally reduce oxide films such as Cr2O3 (the predominant protective film formed on stainless iron, nickel and cobalt alloys) and sulfurous contaminant compounds will react with the oxide films and breach the oxide films allowing the sulfurous contaminant compounds to react with the underlying metal alloys to form low melting sulfides which further degrade the oxide films and the underlying metal alloys that the films are attempting to protect. Thus, there has remained a need to further reduce the hydrocarbon and sulfurous contaminants present on these spinner discs to enhance the formation of oxide films and the integrity of oxide films on the surfaces of the spinner disc to better protect the alloys of the spinner disc from corrosion which may lead to longer service lives for the spinner discs and reduced production costs.
The method of the present invention for making spinner discs for high temperature rotary fiberization processes provides a cost effective method for removing hydrocarbon and sulfurous contaminants from the surfaces of the spinner discs to enhance the formation of better quality protective oxide films on those surfaces after the spinner discs have been fabricated and fiberizing holes formed in the annular peripheral sidewalls of the spinner discs. The method of the present invention includes: forming a spinner disc from an alloy that forms a protective oxide film or films on surfaces of the spinner disc exposed to the atmosphere; forming fiberizing holes in an annular peripheral sidewall of the spinner disc; and applying a plasma to a surface of the spinner disc to remove hydrocarbons and sulfurous compounds from the surface of the spinner disc which would otherwise reduce and/or react with and degrade the protective oxide film or films forming on the surface of the spinner disc when the spinner disc is exposed to the atmosphere (glow discharge cleaning). Preferably, the surface of the spinner disc is solvent cleaned subsequent to the formation of the fiberizing holes and prior to the application of the plasma. The protective oxide film or films form much more rapidly and with greater integrity on the surface of the spinner disc at higher temperatures, e.g. temperatures above 1100xc2x0 F. Accordingly, to minimize or reduce the formation of the protective oxide film or films while the hydrocarbon and sulfurous contaminants are being removed from the surface of the spinner disc by the plasma or glow discharge cleaning treatment of the present invention, preferably, the plasma used to remove the hydrocarbon and sulfurous contaminants from the spinner disc surface is a low temperature plasma of charged particles having a fluorescent light bulb component or plasma source with a temperature only slightly above ambient temperature. Subsequent to removing hydrocarbon and sulfurous contaminants from the spinner disc surface by applying the plasma to the surface of the spinner disc, the spinner disc is heat treated to form a strong continuous oxide film or films on the clean surface of the spinner disc and to strengthen the alloy.